Anti-dam activists in India have stepped up their campaign against the construction of a controversial dam.

India's Supreme Court recently ruled in favour of the Sardar Sarovar dam over the Narmada river, allowing its stalled construction to go ahead.

The judgement of the so-called minority clearly directed that the dam work should be stopped

Narmada Bachao Andolan's Medha Patkar

Medha Patkar of the Narmada Bachao Andolan (Save The Narmada), which has been leading protests against the dam, has begun a five-day hunger strike against the ruling.

"The Supreme Court judgement is divided," Ms Patkar, who leads the movement, told the BBC.

"The judgement of the so-called minority clearly directed that the dam work should be stopped and the clearance that was given was faulty," she said, referring to the 2 to 1 ruling in favour of the dam's construction.

Narmada facts

Project began in 1979

3,200 dams to be built along the 1,200 km Narmada river

Said to benefit Madhya Pradesh, Rajasthan, Maharashtra and Gujarat

Opponents say it will displace 200,000 people and damage ecology

World Bank withdrew funding in 1993

Expected to be fully complete by 2025

The multi-billion dollar Narmada project was launched in 1979 and envisages the construction of some 3,200 small, medium and large dams on the Narmada river.

The Narmada originates in the central Indian state of Madhya Pradesh and empties into the Arabian Sea after flowing through Maharashtra and Gujarat.

The Sardar Sarovar is the biggest dam on the river and its construction has been fiercely opposed.

The Narmada Bachao Andolan says the project will displace 200,000 people in these three states, apart from damaging the region's fragile ecology.

Row over height

A contentious issue is the height of the Sardar Sarovar dam. Its proposed height was 130m, but anti-dam activists do not want the dam to be higher than 88m.

Last week, the Supreme Court ruled that the height of the dam could be raised to 90m but no higher, until cleared by an environmental authority appointed to undertake the task.

Ms Patkar told newspersons in Madhya Pradesh's capital, Bhopal, that the Supreme Court decision to raise the height would affect millions of tribals living in the area.

"The president of India and the governor of the state have a right under Section 5 of the Fifth Schedule of the Constitution to cancel any government decision to protect tribals," she said.

Supporters of the dam say it would provide large amounts of electricity and water to drought prone areas, particularly in Gujarat.